Elastomeric nonwoven laminates are used in a wide variety of applications including extensive use in absorbent articles. For example, such laminates have been used in the topsheet, backsheet, waistband, and fastening elements of absorbent articles. Typical elastomeric nonwoven laminates comprise a layer of nonwoven and a layer of elastic. The layer of nonwoven can provide a feel of softness to a wearer of the absorbent article and may protect a wearer's skin from abrasion caused by the extension and contraction of the elastic.
Elastomeric nonwoven laminates in an absorbent article are subjected to many different forces. For example, in a waistband application, a tension force can be applied to the elastomeric nonwoven laminate such that the waistband is stretched from its non-stretched state to a stretched state. In reaction to the tension force, the waistband provides a contracting force in the opposite direction of the tension force. Specifically, the elastic layer wants to contract to a lower energy state, i.e. a non-stretched state instead of being in a stretched state. The contracting force in turn creates a normal force which acts against a waist of a wearer. The normal force, which is proportional to the contracting force, holds the absorbent article in place about the waist of the wearer. Also, the weight of the absorbent article provides a sagging tension force which tends to pull the absorbent article downward. These sagging tension forces are increased with the retention of body exudates by the absorbent article.
In general, the tension force provided acts in a primary direction of extensibility of the elastomeric nonwoven laminate. The primary direction of extensibility depends greatly on the orientation of the elastic layer and the way in which the elastic layer was bonded to the nonwoven. Typically, the primary direction of extensibility is parallel to a longitudinal axis of the elastomeric nonwoven laminate. In the primary direction of extensibility, the elastomeric nonwoven laminate has the greatest amount of elastic extensibility.
Contrarily, the sagging tension forces act in a direction which is not parallel to the primary direction of extensibility. Instead, the sagging tension forces tend to act more along a secondary direction of extensibility. Because the nonwoven of the elastomeric nonwoven laminate is elastically extensible to a small degree, the elastomeric nonwoven laminate is also elastically extensible in the secondary direction of extensibility. However, because the elastomeric nonwoven is not necessarily intended to be extensible in the secondary direction of extensibility, the elastomeric nonwoven laminate generally has a higher modulus of elasticity (resistance to stretching) in the secondary direction of extensibility than the primary direction of extensibility.
Under initial loading conditions, i.e. fit when the absorbent article is dry, the contracting three exerted by the elastic layer of the waistband creates a sufficient normal force to hold the absorbent article about the waist of the wearer and thereby overcome the sagging tension forces exerted by the unloaded absorbent article. In addition, the nonwoven of the elastomeric nonwoven laminate generally has a modulus of elasticity in the secondary direction of extensibility which is high enough to overcome the sagging tension forces of an unloaded absorbent article.
In contrast, once the absorbent article takes on body exudates and becomes loaded, the sagging tension forces, which are exerted on the waistband and are not in the primary direction of extensibility, are increased. These sagging tension forces may overcome the normal force exerted on the waist of the wearer. Thus, the normal force may not be sufficient to prevent the absorbent article from sagging/slumping on the waist of the wearer. Also, these sagging tension forces, can also overcome the modulus of elasticity of the nonwoven of the elastomeric nonwoven laminate such that the nonwoven is extended in the secondary direction of extensibility. This extension of the nonwoven in the secondary direction of extensibility can exacerbate the sagging slumping effect of the absorbent article on the waist of the wearer.
Also exacerbating this problem is the fact that a wearer's body is contoured. Because a wearer's body is contoured, the forces that are exerted on a nonwoven laminate may not necessarily be distributed evenly across the nonwoven laminate. Thus, the elastomeric nonwoven laminate may experience higher forces on one side of the elastomeric nonwoven laminate and lower forces on another side.
Consequently, it would be beneficial to provide a cost effective elastomeric laminate that can accommodate the tension forces and the sagging tension forces of a loaded absorbent article. Moreover, it would be beneficial to provide an elastomeric laminate that can also better accommodate the contours of a wearer's body. Also, it would be beneficial to provide a method and apparatus for making such a material.